MITSUBISHI MOTOR SALES OF AMERICA, Inc. TECHNICAL SERVICE BULLETIN SUBJECT : STARION ISC AND TPS REVISED ADJUSTMENT PROCEDURE - SERVICE MANUAL UPDATE No: STB-87-14- 011 DATE: October, 1987 MODEL: 1987 Starion CIRCULATE TO: [ ] GENERAL MANAGER [ ] PARTS MANAGER [X] TECHNICIAN [ ] SERVICE ADVISOR [X] SERVICE MANAGER [ ] WARRANTY PROCESSOR [ ] SALES MANAGER PURPOSE This bulletin contains a revised idle speed control (ISC) and throttle position sensor (TPS) adjustment procedure that replaces the procedure shown in the 1987 Starion Service Manual. The new adjustment procedure requires the use of a special tool (Test Harness MD998460) and can be performed faster than the old procedure. As reference to this bulletin, please write the STB number in the revision boxes on pages 14-34, 14-35 and 14-36 of the 1987 Starion Service Manual, Vol. 1 and cross out the old procedure. REVISED ADJUSTMENT PROCEDURE IDLE SPEED CONTROL (ISC) AND THROTTLE POSITION SENSOR (TPS) ADJUSTMENT Adjustment Conditions Engine coolant temperature: 85-95 C (185-205 F) Lights, electric cooling fan and accessories: OFF Transmission: Neutral (N or P for vehicles with an automatic transmission) Steering wheel: Straight ahead (vehicles with power steering) (1)Loosen the accelerator cable to relieve tension.
(2)Disconnect the TPS connector. (3)Connect the special tool (Test Harness MD998459) in series between disconnected connectors. (4)Connect a voltmeter between the red terminal (sensor output) and the black terminal (sensor ground) of the special tool. CAUTION: Use an accurate digital voltmeter. NOTE: The connections between the TPS connector and the special tool are as shown below. TPS connector Special tool Terminal 2 (sensor output) and Red Terminal Terminal 1 (sensor ground) and Black Terminal (5)Connect a tachometer to the engine. (6)Turn the ignition switch ON
(do not start the engine) and hold the switch in that position for 15 seconds or more to check that the ISC servo is set at the initial position (idle point). NOTE: When the ignition switch is turned ON, the ISC servo extends to the fast idle position opening and in 15 seconds, it retracts and stops at the initial position. Initial position: Position corresponding to throttle opening at idle. (7)Turn ignition switch to OFF. (8)Disconnect the ISC servo connector to set the ISC servo at the initial position. (9)Connect the special tool (Test Harness MD998460) to the body harness side ISC servo connector disconnected in step (8). (10) Ground the red terminal of special tool (Test Harness). Remarks: This will allow the
electronic control unit to operate in the same manner as it does when the idle switch is "ON". (11) In order to prevent binding of the throttle valve, open the valve by hand half way or more two or three times and release it to allow it to return with a snap. Then, loosen the fixed SAS so that the throttle linkage does not make contact with the SAS screw. (12) Start the engine and allow it to idle. (13) Check that the engine speed is as specified. Standard value: 850 rpm (14) If the engine speed is not as specified, adjust the ISC adjusting screw until the standard rpm is reached. CAUTION: When turning the ISC adjusting screw, use a hexagon wrench whenever possible. Make this adjustment only when the screw is turned in the tightening direction. (15) Tighten the fixed SAS until the engine speed starts to increase. Then, loosen it until the engine speed ceases to drop (touch point) and then loosen one turn from the touch point. (16) Stop the engine. (17) Turn the ignition switch to ON (do not start the engine) and check that the TPS output voltage is as specified. Standard value: 0.48-0.52 V (18) If it is not as specified, loosen the TPS mounting screws and adjust by turning the TPS.
NOTE: Turning the TPS clockwise increases the output voltage. CAUTION: Securely tighten the screws after adjustment. (19) Turn the ignition switch to "OFF". (20) Adjust the accelerator cable free play. (21) Disconnect the special tool (Test Harness) from the body harness side ISC servo connector. Then, reconnect to the ISC servo connector. (22) Disconnect the special tool (Test Harness) and voltmeter, and then reconnect the TPS connector. (23) Start the engine and check that the idle speed is as specified. Standard value: 850 ± 100 rpm (24) Turn the ignition switch to "OFF". Disconnect the positive battery cable for 5 to 6 seconds and then reconnect it. (This erases the data stored in diagnosis memory during the ISC adjustment.)